BT Call Protect will tackle unwanted calls on such familiar subjects as personal accident claims – the most common category by far according to BT’s data, with 12.3 million calls a week, which is 39% of the total.
The service uses data analysis to identify rogue numbers, which will typically be those used to make large numbers of calls in quick succession, and add them to a blacklist – meaning they are blocked for everyone using Call Protect.
For calls not captured by the technology, users will be able to add the number to their blacklist manually by dialling 1572 after receiving the call. If enough people flag a particular number, it will be added to the overall blacklist.
The service also offers the option to divert whole categories of calls, such as international calls, or those from withheld numbers.
Matt Hancock, minister of state for digital and culture, said: "Nuisance callers are a terrible blight on society and government and industry are working together to crack down on them.
"We’ve forced companies to display their numbers when they call you, made it easier to prosecute those involved in making the calls, and increased the maximum fines up to £500,000.
"We welcome BT's new service, which offers customers an additional level of protection, helping them to fight back against this ongoing harassment."
BT has signed up TV presenter Christine Lampard as its ambassador to promote the service. Lampard said she was motivated to help fight back against the problem by its impact on her own parents.
According to research carried out for BT, more than a quarter of people are concerned about their parents or grandparents getting nuisance calls, in case they are conned.
John Petter, chief executive of BT Consumer, said: "We’re declaring war on the companies that regularly pester our customers with nuisance calls on subjects such as PPI and personal accident claims. We’re giving our customers the means to fight back against the millions of unwanted calls for free.
"We’ve been at the forefront of equipping our customers to defend themselves against the huge numbers of PPI and unwanted marketing calls that are continuing to grow. Now, with our unique technology, we can identify and tackle huge numbers of those calls in the network and also give our customers control over the calls they receive.
"We’re leading the way and calling on other telecoms companies to up their game in the fight against this menace."